Where do our emotions come from? Scientists addressing this long-standing philosophical question recently got some answers by using—bear with us—videos of people licking vomit off their fingers and other revolting scenarios.

Human emotions are associated with measurable changes in heart rate, gut motility and sweat gland secre­tions, but some experts have argued that these bodily responses are simply a general stress reaction and therefore cannot account for different types of emotions. A Journal of Neuroscience study from September 22 suggests otherwise, presenting evidence of distinct physiological signatures of two forms of disgust.

Neuroscientist Neil Harrison and his colleagues at the University of Sussex in England monitored heart rate, stomach contractions and brain activity as study participants viewed videos designed to elicit two kinds of disgust. The vomit video and other gross-out films elicited what is known as core disgust; videos of surgical operations—such as an above-knee amputation—induced body-boundary violation (BBV) disgust. Although both types of videos were judged as equally revolting, core dis­gust evoked strong increases in stomach contrac­tion, whereas BBV elicited increases in heart rate. If these bodily changes form the basis of our emotional experiences, the researchers predicted that disgust-specific brain activity should reflect similar patterns. They found this very type of activity in the insula, an area deep in the brain where infor­mation about the body intersects with that about emotions.

The findings support the idea that these bodily responses are more than generalized arousal: they can form the outlines of specific emotions. Our own cognitive interpretations of the scene may then add to these physical responses to create a full-fledged emotion. “These bodily responses are not going to be the whole story of where our emotions come from, but they provide a kind of skeleton,” Harrison says. [For more on embodied cognition, see “Body of Thought,” by Siri Carpenter.]

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